Apparatus for the electrical treatment of colloidal dispersions



Oct. 12, 1943.

E. A. MURPHY AL 2,331,494

APPARATUS FOR THE ELECTRICAL TREATMENT OF COLLOIDAL DISPERSION Filed Nov. 15; 1941 r Even/Z075 EDWARD ARTHUR MURPHY, FREDERICK dmss -Pnrow,

- stuffs, metals and resins, such Patented Oct. 12, 1943 UNITED STATES PATIENT; orrica APPARATUS FOR 2,331,494. 7 I THE ELECTRICAL TREAT-Q MENT F COLLOIDAL DISPERSIONS Edward Arthur Murphy, Wylde Green, England, .and Frederick James Paton and John Ansell,

Batu Anam, Johore, assignors to Dunlop Rub ber Company Limited, London, England, a com- 1 pany of Great Britain Application November 15, 1941, Serial No, 419,258 In Great Britain April 19, 1940 4 Claims.

.coagulated rubber, vulcanized rubber,-synthetic rubber waste or reclaim may also be used if de-' sired as alternatives or admixtures; and any of ,these dispersions may contain the usual compounding ingredients.

More particularly'the invention relates tothe electro-creaming of rubber latex in apparatus comprising a number or multiplicity of diaphragms between which such dispersions are submitted to a difference in electrical potential to effect the creaming.

As rubber latex is, therefore, an example 'of the above type of dispersion, the term latex is used hereinafter to designate the dispersion to be treated. The concentrate produced or obtained in the apparatus is called the cream.

In our invention the period of time during which the apparatus may be operated efllciently without stopping is very greatly increased.

In our invention also we make provision whereby the individual diaphragms can be cleaned or replaced without interrupting the operation of the apparatus. The diaphragms are so arranged as to be readily removable from, and replaceable in, a vat or cell containing the latex. For this purpose a cell is preferably arranged in such a way that the diaphragms are readily accessible therein and the cell has an open top, or readily removable lid, to permit the diaphragms to be conveniently lifted.

To prevent a skin formation on a free surface of the latex, a surface disturber is provided to sweep through the surface. The above arrangement permits the use of weirs at the edge of the free surface ouer which weirs the cream decants. I

In our apparatus the diaphragms are preferably pendant or hang freely and are completely submerged. Each may comprise a sheet of suitable permeable material, such as "Cellophane sheets. The top edge'of each sheet carries'a member which spans the cell'ortank' and has projecting ends that fit or rest in slots in the cell walls and thus supports the sheet in fixed position in the latex. "The bottom edge of the sheet is weighted which causes the sheet to hang true in the latex. The upper supporting memberand the lower weighting member are 'conveniently carried in'tubularhems formed on the upper and lower edges of the sheet respectively, or may be associated or combined with said sheet in any other suitable way. The bottom, weighting, member may comprise a simple rod, and the top,

. supporting, member may comprise a slat carry ing lugs to facilitate handling.

To clean or replace a. diaphragm that is becoming. clogged-it is merely lifted out of the cell as, for example, by hand or mechanically, where upon it may be cleanedorlreplaced by another.

In/general, the diaphragmsrmay be arranged in any one of the various ways'as described in our co-pending application Serial No. 419,268, filed on even date herewith.

In using an open top cell in which the diaphragms are readily accessible, the cell maycomprise a suitable receptacle or compartment partitioned adjacent each, end wall to house the electrodes and provided adjacent each said wall 'with a slotted rack to support the diaphragms.

A suitable loose lid may be provided if desired.

To disturb the surface and to prevent skin forming, a blade having one edge submerged in the latex may be reciprocated slowly along the cell by any suitable means as, for example, by a reversing screw and nut mechanism. Flanking each of the racks aforesaid is a weir over which the cream flows into longitudinal fiumes which may deliver into a single transverse fiume leading .to a suitable container for the cream.

As the current acts on the latex the disturbed particles, such as rubber, float to the surface layers and collect there as a cream of the required consistency. This cream then flows over the weirs under the influence of a head of the supply feed. The'surface disturber may aid in easing the cream over the weirs.

The latex is fed to the apparatus and the separated serum drawn away under suitable control means. For this purpose any of the known means in the art, such as a float chamber adjacent the head or meters to indicate the condition of the respective dispersions flow to and 1 from the apparatus, may be used.

drawing comprising a perspective view of an apparatus embodying the" invention.

In the drawing a vat or cell or tank I is provided with a multiplicity of pendant diaphragms normally submerged below the liquid level in the vat or cell, one of which is shown as at I, slightly raised from its submerged position. When in submerged position the diaphragms are supported by a supporting member 3 extending throughout the upper edge of the diaphragms and projecting therefrom on each side and supported in slots, a series of which are arranged as at 4, at each side of the tank or cell. A surface disturber 5 for preventing skin formation on the free surface of the latex is mounted so as to be reciprocated along the cell by the mechanism 6 comprising a reversing screw and nut. At each end of the vat or cell I, a weir I is provided over which the cream may decant. To enable the diaphragms to be completely submerged and permit the disturbing member 5 to pass freely over their upper edges, the projecting ends of the supporting member 3 are extended outwardly and upwardly to form the lugs 8. This also facilitates the handling of the diaphragm.

Latex is supplied to the cell or tank through piping 9 and may be withdrawn from the bottom of the tank through a draw-off pipe 9'. The electric current for causing the creaming is supplied to electrodes in at the opposite ends of the vat or cell.

From the above it will be apparent that our invention provides apparatus in which the diaphragms are so held in freely pendant or suspended arrangement that any one of them may be lifted without disturbing the others and may be thus cleaned and replaced or substituted by another. Also the cream not only overflows into the weirs, but a uniform sweeping of the entire surface over the weirs by the disturber 5 prevents any of the surface cream remaining to form a skin.

Having described our invention, what we claim 1. Apparatus for the electrical treatment of colloidal dispersions comprising a container, a multiplicity of diaphragms suspended in spaced relation in said container, electrodes at opposite ends of said container, weirs on opposite sides of said container and ablade movable in the liquid surface of said container alternately toward one and the other of said weirs.

2. Apparatus for the electrical treatment of colloidal dispersions comprising a container having overflow weirs, supply piping below the level of said weirs and draw-off piping below the level of said supply piping,'a number of diaphragms suspended in said container in spaced position and completely below the overflow level of said weirs, electrodes extending to said container and a blade moving in the level of the overflow of said weirs toward and from said weirs.

3. The apparatus of claim 2 in which said container is open.

4. Apparatus for the electric treatment of colloidal dispersions comprising a container having overflow wiers on opposite sides, diaphragms suspended in said container entirely below the level of said overflow wiers and in spaced parallel relation between said overflow wiers, electrodes at opposite ends of said container, and means movable above the upper ends of said diaphragms at the overflow level of said wiers to move the surface of liquid therein toward said wiers.

FREDERICK JAIWES PATON. JOHN ANSFIL. 

